Some smartphones and other devices, particularly portable devices, are capable of communicating with one another using near field communication (NFC). The devices may communicate with each other when touching the devices together or by bringing the devices into close proximity with one another. In certain examples, the communication range for near field communications is about 10 centimeters. According to one standard, near field communication devices use electromagnetic induction between two loop antennas in the respective devices to communicate in the radio frequency band of 13.56 MHz. Some of the devices may be passive with no battery of their own but may harvest energy for their operation from the other communicating device through the magnetic induction.
Effective near field communication requires generation of a relatively large magnetic field by the antenna, for example, to be able to power battery-less passive NFC devices. Portable devices such as smartphones tend to have small volumes in which to fit antennas. The requirement to generate the large magnetic field from a small antenna in a battery operated device has resulted in near field communication circuits that have a high cost, particularly for the radio frequency (RF) power amplifier component and the voltage regulator component of the near field communication device. In addition to high costs, operating the near field communication devices result in high power dissipation and thus battery drain due to relatively low efficiencies in the RF power amplifier and the voltage regulator. The heat generated by the power dissipation of the low efficiency components results in thermal issues, i.e. the requirement to provide cooling and the need to provide circuit elements that will operate when subject to thermal stress.